Ball mill



C. A. DUNCAN AND ALNELSON.

BA LL MILL.

. APPLICATION FILED AUG.6. 1921. 1,412,390, Patented Apr. 11, 1922. v

UNITED STATES PATENT OFFICE.

CHARLES A. DUNCAN AND ALFRED, NELSON, OF WALLACE, IDAHO.

BALL MILL.

T 0 (LE 10 7mm it may concern. 7

Be it known that we, CHARLES A. DUNCAN and ALFRED NELSON, citizens ofthe United States of America, residing at lVallace, 1n the county ofShoshone and State of Idaho, have invented certain new and usefulImprovements in Ball Mills, of Which the following is a specification.

This invention relates to an improvement in ball mills and moreparticularly to the provision of an improved arrangement of helix in theoutlet trunnion of such a null.

In the ball or pebble mills commonly in use a helix is usually formed inthe outlet trunnion, the function of which is to prevent the balls orpebbles in the mill from passing out through the outlet trunnion andthrough which trunnion the water and mill feed are discharged. However,in order for the water and mill feed to pass out over the helix suchwater and mill feed has to accumulate in con- Siderable quantity and itis frequently the case that the balls or pebbles pass out along with themill feed.

It is the primary object of the present 1nvention to provide a helix ofsuch a nature as will permit the escape of the water and the mill feedand will effectually prevent the escape of the balls or pebbles.

Further objects and advantages of the invention will be set forth in thedetailed description which follows.

In the accompanying drawing:

Fig. 1 is a view in side elevation of the outlet trunnion of a ball orpebble mill and the bearing in which it is mounted;

Fig. 2 is an enlarged sectional view illustrating a slightly modifiedform of trunnion; and

Fig. 3 is an end elevation of the construction shown in Fig. 2.

Like numerals designate corresponding parts in all of the figures of thedrawing.

The invention resides in disposing in the outlet trunnion 5 of aconventional ball or pebble mill, a helix 6, the outer periphery of saidhelix being spaced from the inner pcriphery of the trunnion to leave aspace 7 between the helix and the trunnion through which the water andmill feed may find its way but through which the balls or pebbles in themill cannot pass. It is immaterial what particular means are employed tohold the helix in spaced relation to the wall of the trunnion. As onemeans of accomplishing this result, we have illustrated set screws 8.

Specification of Letters Patent. Patented, Apr. 11, 1922.

Application filed August 6, 1921.

Serial No. 490,437.

we do not claim, broadly, the idea of includ ing a helix in the outlettrunnion of a ball mill, because this we know to be old. However, so faras we are aware, it is new to mount a. helix in the outlet trunnion of aball mill in such manner that the helix will always tend to feed theballs back into the mill, if they tend to escape and to space such helixfrom the inner periphery of the outlet trunnion in the manner hereindescribed.

An additional advantage of the arrangement recited is that the balls orpebbles may be fed into the mill whenever desired by merely insertingthem in the outlet trunnion and letting them come within the range ofthe action of the helix.

It is to be understood that the invention is not limited to the preciseconstruction set forth but that it includes within its purview whateverchanges fairly come within either the terms or the spirit of theappended claims.

Having described our invention, what we claim is:

1. The combination with the outlet trun nion of a ball mill, of a helixdisposed therein the outer periphery of which lies in spaced relation tothe inner periphery of the trunnion, leaving a passage for materialthrough the trunnion between the inner periphery of the trunnion and thehelix, said helix being open at its sides between its convolutions toestablish free communication between the interior of the helix and saidpassage 2. A structure as recited in claim 1 in combination with spacingelements carried by the helix and engaging the wall of the trunnion forholding said helix in spaced relation to said wall.

8. The combination with the outlet trunnion of a ball mill, of a helixdisposed therein and means for holding the helix in spaced relation tothe inner periphery of the trunnion to leave an opening bet-ween thehelix and trunnion substantially entirely therearound and from end toend of the trunnion to permit the passage of material from the interiorof the mill to the exterior thereof between said helix and the wall ofthe trunnion, said helix being open at its sides between itsconvolutions to establish free eom munication between the interior ofthe helix and said first named opening.

4L. In combination a ball mill having an outlet element of tubularformation, a helix disposed in said outlet elementand means for holdingthe helix in spaced relation to the inner periphery of the said elementto leave an opening between the helix and elementsubstantially entirelyaround thehelix and fromend to end of the element to permit the passageof material from the interior of the mill to the exterior thereof be-CHARLES A. DUNCAN. ALFRED NELSON.

Witnesses as to Charles A. Duncan:

H. J. HULL J. M. PEARCE.

WVit-nesses as to Alfred Nelson:

CHARLES MooNEN, A. P. MITCHELL.

